1. Technical Field
The disclosure generally relates to optical lenses, and particularly relates to an optical lens to increase an illuminating angle of a light source and a light source module having the optical lens.
2. Description of Related Art
In recent years, due to excellent light quality and high luminous efficiency, light emitting diodes (LEDs) have increasingly been used as substitutes for incandescent bulbs, compact fluorescent lamps and fluorescent tubes as light sources of illumination devices.
Generally, light intensity of a light emitting diode gradually decreases from a middle portion to lateral sides thereof. Such a feature makes the LED unsuitable for functioning as a light source which needs a wide illumination, for example, a light source for a direct-type backlight module for a liquid crystal display (LCD). In some conditions, it is required to have an optical lens which can help the light emitted from a light emitting diode to have a wider illuminating angle. However, part of the light enters into the optical lens in a large angle relative to an optical axis of the light emitting diode, and leaves from the optical lens uselessly.
What is needed, therefore, is an improved optical lens and a light source module having the optical lens to overcome the above described disadvantages.